[HH] WWVB repeater or emulator

[Tom Metro]

I have several clocks in my house (and a watch) that all set their time
using the 60 kHz radio broadcast time signal originating from Fort
Collins, Colorado (callsign WWVB).

http://en.wikipedia.org/wiki/WWVB

One clock reliably gets the signal, but the others don't, and it seems
like over the last decade, the signal has diminished, as they used to.
Jon 'maddog' Hall assured me via Twitter that he receives the signal
just fine in NH, so it may be local signal interference, or changes in
buildings or trees that have diminished the signal in the Boston area.

Oddly enough, according to Wikipedia, the transmitter power was actually
increased in 2005. Sure seems like it worked better before then.

The page notes that they recently introduced phase-shift keying
modulation, which "allows a more sophisticated receiver to distinguish 0
and 1 bits far more clearly, allowing improved reception on the East
Coast of the United States where the WWVB signal level is weak, radio
frequency noise is high, and the MSF time signal from the U.K. also
interferes sometimes." Maybe I'm getting interference from the UK?

And: "WWVB's Colorado location makes the signal weakest on the U.S. east
coast, where urban density also produces considerable interference. In
2009, NIST raised the possibility of adding a second time code
transmitter, on the east coast, to improve signal reception there and
provide a certain amount of robustness to the overall system should
weather or other causes render one transmitter site inoperative. Such a
transmitter would use the same time code, but a different frequency."

This hasn't happened, but when/if it does, using a different frequency
means my existing devices won't receive it anyway.


In any case, I've periodically searched online to see if anyone has
built a circuit that either acts as a repeater for the WWVB signal, or
emulates it, using a GPS receiver or Internet NTP server as a time
source. I haven't searched in a year or more, but last time I did I ran
across a description of a graduate student project to build a repeater.

Anyone seen a circuit or product that does this?

With small, hacker friendly Linux devices becoming increasingly cheap,
it should be quite possible to hit a sub-$50 price point for such a
device, providing the AM transmitter doesn't require much.

For something like this I'd rather buy a finished product, or at least a
kit with the radio supplied as a built module, as I don't have the
equipment to debug an RF transmitter.

 -Tom